Fuel injection pump for internal-combustion engines

ABSTRACT

In a fuel injection pump in which the fuel quantities delivered thereby to an internal-combustion engine are controlled by a throttle opening arbitrarily variable by means of a control plunger, there is associated with said plunger a heat expandable part which, independently of the arbitrary setting of said plunger, causes a displacement of the plunger in response to the changes in the temperature of the liquid passing through said throttle in order to compensate for the temperature-dependent changes in the viscosity of said liquid.

I United States Patent 1 1 3,628,892

[72] Inventor Franz Eheim [56] References Cited Stuttgart, GermanyUNITED STATES PATENTS 1211 pp 5 1" 1970 2,980,173 4/1961 Perkey 137/4681 Filed 51,197] 3,082,787 3/1963 Elston etal. 137/468 222F252: zg' kGmbH 3,340,893 9/1967 LOCkWOOd.. l37/468 Stuttgart, Germany 3,096,7l67/1963 Chmura 417/292 [32] Priority Feb. 28, 1969 PrimaryExaminer-Carlton R. Croyle [33] Germany Assistant Examiner-John J.Vrablik [3 l] P 19 I0 090.4 AnorneyEdwin E. Greigg 54 FUEL INJECTIONPUMP FOR INTERNAL- ABSTRACT: In a fuel injection pump in which the fuelquantil COMBUSTION ENGINES tles delivered thereby to aninternal-combustion engine are 5 Claims, 2 Drawin Figs. controlled by athrottle opening arbitrarily variable by means g f l l h d h d l 0 acontro p unger, t ere is associate wit sai p ungcr a [52] U.S.Cl4411770229921; heat expandable P which independently of the arbitrary 5]l t Cl F04) 49/00 setting of said plunger, causes a displacement of theplunger in 417/292 response to the changes in the temperature of theliquid l ie 0 .593 137/468, p g through Said throttle in order tocompensate for the temperature-dependent changes in the viscosity ofsaid liquid.

FUEL INJECTION PUMP FOR INTERNAL-COMBUSTION ENGINES BACKGROUND OF THEINVENTION This invention relates to a fuel injection pump forinternalcombustion engines and is of the type wherein the fuel quantityto be delivered to the engine is affected by an arbitrarily displaceablecontrol plunger which, by means of a control edge, varies a throttledetermining the flow rate of a liquid.

In a known fuel injection pump of this type (as disclosed, for example,in Austrian Pat. No. 227,480), the fuel quantities to be injected aredetermined by opening a bypass channel of the pump work chamber by meansof a regular shuttle. The latter is caused to execute its forwardstrokes by a regulating liquid driven by an auxiliary pump whichoperates synchronously with the main fuel pump. During its returnstrokes, the regulator shuttle is braked by directing at least one partof the regulating liquid that caused its preceding forward strokethrough the aforenamed variable throttle. As a result, for apredetermined flow passage section of said throttle and upon reaching apredetermined r.p.m., the regulator shuttle, due to the appearance of aso-called fluid abutment, does no longer return into its originalposition of rest. In such a case, the forward strokes of the regulatorshuttle start from an advanced position of rest. As a result, the bypasschannel of the pump work chamber is opened at an earlier moment andconsequently, the delivered fuel quantities are decreased.

The magnitude of the flow rate through any given flow passage section ofthe throttle depends upon the viscosity of the liquid. As long as theregulating liquid is relatively cold and thus of relatively highviscosity (for example, during starting of a cold internal-combustionengine), the fluid abutment increases rapidly in case of a flow passagesection set for idling. Consequently, the fuel quantities to be injecteddrop sharply. This is disadvantageous because the cold engine, due tothe higher hysteresis, needs a greater quantity of fuel.

The foregoing applies not only to fuel injection pumps in which fuelquantity control is performed with the aid of a separate regulatingfluid circuit, but also for pumps regulated by means of a suctionthrottle. In the last-named structures the flow rate of the fuel througha predetermined flow passage section depends upon the temperature of thefuel.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention toprovide an improved fuel injection pump wherein the flow passage sectiondetermining the liquid flow varies automatically with the operatingtemperatures and thus with the change of the liquid viscosity, adjustingthereby the engine r.p.m.

Briefly stated, according to the invention, the throttle control meansis formed of a first part which is arbitrarily adjustable, a second partwhich is a plunger that includes a control edge and a third part whichis a heat expandable member causing relative displacements between thefirst and second parts as the temperature of the liquid passing throughthe throttle changes. As a result, a temperature-responsive change inthe flow passage section of the throttle is obtained.

In addition to improve the starting conditions of the engine, theaforenoted adjustment of the engine r.p.m. is also advantageous in themaximum r.p.m. range to eliminate substantial fluctuations.

The invention will be better understood, as well as further objects andadvantages will become more apparent, from the ensuing detailedspecification of two exemplary embodiments of the invention taken inconjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I in an axial diagrammaticsectional view of a fuel injection pump including it throttle controlmeans forming the first embodiment of the invention; and

FIG. 2 is an isometric view of a throttle control means according to asecond embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS A pump housing 1 is provided with a bore2 in which operates a main pump piston 3 driven by a mechanism (notshown) in such a manner that it executes an axial reciprocating motionas well as a rotary motion. Into bore 2 there merge an inlet channel 4and a certain number of output or delivery channels 5, each of thelatter containing a check valve 6. For the purpose of establishingcommunication between the pump work chamber 20 and one of the deliverychannels 5 during during each pressure stroke of piston 3, there isprovided a longitudinal distributor groove 7 on the outer face of thepiston 3. Further, for the fuel supply of the pump work chamber 2aduring the return stroke of piston 3, the latter is connected with thesupply channel 4 through an axial channel 8 which, on the one hand,merges in the pump work chamber 20 and, on the other hand, terminates ina transversal channel 9 which establishes communication with the supplychannel 4 through an annular groove 10 and axially extending grooves 11.

To control the fuel delivery of the fuel injection pump during thepressure strokes of the pump piston 3, there is provided a regulatorshuttle 12 which operates in a cylinder 13 and which controls a bypasschannel formed of two channel portions 14a and 14b. The bypass channelportion 14a connects the pump work chamber 2a with the cylinder 13,while the bypass channel portion 14!: connects the cylinder 13 with achamber of lower pressure.

To cause forward strokes of the regulator shuttle 12, there is provideda regulating liquid which is delivered in a pulsating mannersynchronously with the pressure strokes of the main pump piston 3. Theregulating liquid is driven by means of an auxiliary piston 15 which isformed as a stepped portion of piston 3 and which operates in a cylinder16. From the latter there extends a delivery conduit 17 through a checkvalve 18 to the lower end portion of the cylinder 13. A supply conduit19 merges in the cylinder 16 and is controlled by the auxiliary piston15.

Further, the cylinder 16 communicates with the lower end portion of thecylinder 13 by means of a channel 20 which leads from cylinder 16 to acylinder 21 and by means of a channel 22 extending from cylinder 21 tocylinder 13. The opening through which the channel 20 merges into thecylinder 21 is throttled at 23. The free flow passage section ofthrottle 23 may be varied by the control edge 24a of a control plunger24, the axial position of which may be set by means of a screw 25. Tothe latter there is affixed a pin 34 which may be connected with amechanism (not shown) for the arbitrary actuation of screw 25.

The regulating liquid delivered by the auxiliary pump 15, 16 causes aforward stroke of the regulator shuttle 12 against the force of a returnspring 26 which tends to maintain the regulator shuttle 12 in itsposition of rest determined by an abutment 27.

The forward stroke of the regulator shuttle 12 is terminated at themoment when its lower control edge 12a opens a bypass channel 28. At themoment when the regulator shuttle l2 establishes communication betweenthe two bypass channel portions 14a and 14b by means of the control edge12b, the fuel delivery from the pump work chamber 2a through thedelivery channel 5 is interrupted, since the fuel, during the remainderof the pressure stroke of piston 3, is driven thereby through the bypasschannel 14a, 14b.

The return stroke of the regulator shuttle 12 is braked by theregulating liquid which is displaced from the cylinder 13 through thethrottle 23 by the returning regulator shuttle 12. Beyond a determinedoperational speed of the pistons 3 and 15. the regulator shuttle 12, dueto the aforenoted braking effect, will be forced by the regulatingliquid to execute the next forward stroke before returning to itsinitial position of rest determined by the abutment 27. This phenomenonis the socalled fluid abutment, by virtue of which the stroke of theregulator shuttle l2 necessary for establishing communication betweenthe bypass channel portions 14a and 14b becomes shorter. It will beunderstood that the more the operating speed of the pistons 3 and 15increases for the same flow passage section of throttle 23, the shorterwill be the aforenoted stroke of the regulator shuttle 12.

The r.p.m. of the engine is determined by the setting screw 25. To eachposition of screw 25 and thus to each flow passage section of throttle23, there corresponds a certain rpm. The regulating fluid, however, ismore viscous in a cold condition than at normal temperatures so that incase of a cold regulating liquid because of the more viscous and thussmaller fuel quantities flowing through the throttle 23 during eachreturn stroke of the regulator shuttle 12, the fluid abutment rises morerapidly and the fuel injection pump cuts off earlier. in case of a coldengine such occurrence leads to stalling.

in order to prevent such a disadvantageous effect, according to theinvention, between the control plunger 24 and the setting screw 25 thereis disposed, in engagement with both, a heat expandable member 30. Thelatter, which may be made of a synthetic material or metal (bimetallicelement) expands in response to warmer temperatures and contracts atcolder temperatures. Such changes in the dimension of the heatexpandable part 30 cause an axial shift of the control plunger 24varying the flow passage section of throttle 23. In this manner it isachieved that for a given setting of screw 25, the flow passage section23 is smaller at higher temperatures than at lower temperatures. Thus,the viscosity differences of the regulating liquid caused by thetemperature variations are compensated and, as a result, the throttlingfunction of the regulator shuttle 12 is not affected by the temperatureof the regulating liquid. Stated in other terms, under identical engineloads, a certain setting of the screw 25 always corresponds to onecertain r.p.m.

Turning now to FIG. 2, there is shown a second embodiment of thethrottle control means associated with throttle 23. This throttlecontrol means comprises a control plunger 24' and a setting screw 25having a first head segment 31 integral therewith. A second head segment32 is held concentrically and coplanar with the first head segment 31and is rotatable relative thereto. Between the two segments 31 and 32there is disposed a heat expandable member 33 also having a segmentlikeconfiguration. As the segment 33 expands or contracts in response totemperature changes of the regulating liquid, the head segments 31 and32 are displaced angularly with respect to one another. As a result, thecontrol plunger 24' is dis placed varying the flow passage section ofthrottle 23.

To the segment 32 there is affixed a pin 34 by means of which the screw25 may be arbitrarily turned and thus the flow passage section ofthrottle 23 varied.

Any setting force exerted on pin 34 is transmitted by the segment 32 onthe segment 31 through the heat expandable segment 33. Each angularposition of the segment 32, that is, each position of the pin 34,

corresponds for the same load conditions to one certain r.p.m., sincethe temperature differences which determine the viscosity of theregulating liquid are compensated by means of the heat expandablesegment 33 in a manner described in connection with the firstembodiment.

What is claimed is:

1. In a fuel injectibn pump associated with an internal-combustionengine, the improvement comprising,

A. a piston delivering fuel, during its pressure strokes, to

said engine,

B. means for controlling the fuel quantity delivered to said engine bysaid piston during its pressure strokes, said lastnamed meansincluding 1. a variable throttle opening determining the flow rate offuel passing therethrough for setting said fuel quantity, 2. a movablecontrol plunger adjacent said throttle opening for varying the flowpassage section thereof, 3. an arbitrarily movable part connected withsaid control plunger for setting the flow passage section of saidthrottle opening to a desired value and 4. a heat expandable memberresponsive to the temperature change of said fuel, said heat expandablemember being in engagement with said control plunger to causedisplacement thereof relative to said arbitrarily movable part forvarying said flow passage section upon variations of said temperature.

2. An improvement as defined in claim 1, wherein said heat expandablemember is in engagement with said arbitrarily movable part to constitutea motion transmitting means between said arbitrarily movable part andsaid movable control plunger.

3. An improvement as defined in claim 2, wherein said heat expandablemember is disposed axially between said control plunger and saidarbitrarily settable part; the changes in dimension of said heatexpandable member effect an axial displacement of said control plungerwith respect to said arbitrarily settable part.

4. An improvement as defined in claim 2, wherein said control plunger isintegral with a threaded portion or screw to be axially displaced byrotation and with a segment head; said arbitrarily settable part isformed as a segment member arranged adjacent and rotatable with respectto said segment head, said heat expandable member has a segmentconfiguration and is inserted between said segment head and said segmentmember, the changes in dimension of said heat expandable member effectan axial displacement of said control plunger by rotation with respectto said arbitrarily settable part.

5. In a fuel injection pump associated with an internal-combustionengine, the combination comprising A. a main piston delivering fuel,during its pressure strokes,

to said engine,

B. a pump work chamber from which said fuel is displaced by said mainpiston,

C. a bypass channel extending from said pump work chamber,

D. a regulator shuttle executing alternating forward strokes and returnstrokes, said regulator shuttle opening said bypass channel during saidforward strokes to interrupt delivery of fuel from said pump workchamber to said engine during one part of each pressure stroke of saidmain piston,

E. a regulating liquid,

F. an auxiliary piston operating synchronously with said main piston anddriving said regulating liquid with an rpm-dependent pressure againstsaid regulator shuttle to cause the forward strokes thereof,

G. return means exerting a force on said regulator shuttle against thepressure of said regulating liquid,

H. a return channel,

I. an arbitrarily variable throttle in said return channel; saidregulator shuttle being braked during its return strokes, by saidregulating liquid forced by said regulator shuttle through said returnchannel and said arbitrarily variable throttle and arbitrarilydisplaceable means to vary the flow passage section of said throttle,said last named means including l. a control plunger to directly varysaid flow passage section by displacement and 2. a heat expandablemember responsive to the temperature changes of said regulating liquidand in engagement with said control plunger to cause displacementthereof upon variations of said temperature.

t I i i i

1. In a fuel injection pump associated with an internalcombustionengine, the improvement comprising, A. a piston delivering fuel, duringits pressure strokes, to said engine, B. means for controlling the fuelquantity delivered to said engine by said piston during its pressurestrokes, said lastnamed means including
 1. a variable throttle openingdetermining the flow rate of fuel passing therethrough for setting saidfuel quantity,
 2. a movable control plunger adjacent said throttleopening for varying the flow passage section thereof,
 3. an arbitrarilymovable part connected with said control plunger for setting the flowpassage section of said throttle opening to a desired value and
 4. aheat expandable member responsive to the temperature change of saidfuel, said heat expandable member being in engagement with said controlplunger to cause displacement thereof relative to said arbitrarilymovable part for varying said flow passage section upon variations ofsaid temperature.
 2. a movable control plunger adjacent said throttleopening for varying the flow passage section thereof,
 2. An improvementas defined in claim 1, wherein said heat expandable member is inengagement with said arbitrarily movable part to constitute a motiontransmitting means between said arbitrarily movable part and saidmovable control plunger.
 2. a heat expandable member responsive to thetemperature changes of said regulating liquid and in engagement withsaid control plunger to cause displacement thereof upon variations ofsaid temperature.
 3. An improvement as defined in claim 2, wherein saidheat expandable member is disposed axially between said control plungerand said arbitrarily settable part; the changes in dimension of saidheat expandable member effect an axial displacement of said controlplunger with respect to said arbitrarily settable part.
 3. anarbitrarily movable part connected with said control plunger for settingthe flow passage section of said throttle opening to a desired value and4. a heat expandable member responsive to the temperature change of saidfuel, said heat expandable member being in engagement with said controlplunger to cause displacement thereof relative to said arbitrarilymovable part for varying said flow passage section upon variations ofsaid temperature.
 4. An improvement as defined in claim 2, wherein saidcontrol plunger is integral with a threaded portion or screw to beaxially displaced by rotation and with a segment head; said arbitrarilysettable part is formed as a segment member arranged adjacent androtatable with respect to said segment head, said heat expandable memberhas a segment configuration and is inserted between said segment headand said segment member, the changes in dimension of said heatexpandable member effect an axial displacement of said control plungerby rotation with respect to said arbitrarily settable part.
 5. In a fuelinjection pump associated with an internal-combustion engine, thecombination comprising A. a main piston delivering fuel, during itspressure strokes, to said engine, B. a pump work chamber from which saidfuel is displaced by said main piston, C. a bypass channel extendingfrom said pump work chamber, D. a regulator shuttle executingalternating forward strokes and return strokes, said regulator shuttleopening said bypass channel during said forward strokes to interruptdelivery of fuel from said pump work chamber to said engine during onepart of each pressure stroke of said main piston, E. a regulatingliquid, F. an auxiliary piston operating synchronously with said mainpiston and driving said regulating liquid with an r.p.m.-dependentpressure against said regulator shuttle to cause the forward strokesthereof, G. return means exerting a force on said regulator shuttleagainst the pressure of said regulating liquid, H. a return channel, I.an arbitrarily variable throttle in said return channel; said regulatorshuttle being braked during its return strokes, by said regulatingliquid forced by said regulator shuttle through said return channel andsaid arbitrarily variable throttle and J. arbitrarily displaceable meansto vary the flow passage section of said throttle, said last named meansincluding